Steam generator unit



3 Sheets-Sheet l J. E. KENNEDY STEAM GENERATOR UNIT f fuwnmxufhpf...

May 1, 1951 Filed Maroh 3, 1945 I Ai.\\\\\\\\\\\\` INVENTOR JOJEPH t'. KENNEDY ATTORNEYS BY f WwW/MVM J. E.` KENNEDY 2,551,137

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STEAM GENERATOR UNIT Filed March 3, 1945 5 Sheets-Sheet 3 ATTORNEYS Patented May 1, 1951 UNITED lS TAT ES TENT OFFICE y STEAM GENERATOR UNIT Application March 3, 1945', Serial No. 580,740

2 Claims.

My invention relates to improvements in steam generator units for large scale production of steam and superheated steam.

= Steam generator installations for large scale use, such as those used in power plants and similar installations, involve very substantial investments. Such installations are commonly constructed with two or more relatively large water drums mounted in the lower part of the setting in addition to at least one steam and water drum at the upper part of. the setting. Drums of this type not only involve the use of relatively large quantities of steel, but also add considerably to the investment in the plant and thecost of erection.

I have discovered that a large scale plant can be successfully built and operated without using water drums in the lower part of the generator setting and at the same time maintain a high efficiency for the installation.

Theprimary object, therefore, of my invention, is to provide improved steam generator unit which includes but a single steam and water drumwhich is mounted in the upper part of the setting. A y l A further object of my invention is to provide an improved steam generator unit for the production of steam and superheated steam on a large scale and which is relatively economical to build and in which the high efficiency of such units is maintained.

Another object of my invention is to provide an improved steam generator unit having a single combustion chamber which can be fired with powderedsolid fuels or liquid fuels and in which improved means are provided in combination with a single drum for absorbing the Vradiant heat produced. Y Y

An important feature of my present'invention is the provision of a steam generator unit having a single firing furnace chamber, the wallsrof which are comprised of steam generating tubes closely mounted together, a single drum for the generator unit mounted in the upper portion of the combustion chamber, and steam generating tubes mounted along the chamber walls in spaced relation to the Wall tubes and to each other,y whereby aconsiderable proportion of the heat developed in the combustion chamber is absorbed by the spaced tubes without appreciably reducing the heat absorption capacity of the wall tubes. y

Another feature of my invention includes the provision in a steam generator unit as described above of a bank of steam superheatng tubes, and in which means is provided for passing hot furnace gases from the furnace combustion chamberupwardly through the bank of superheater tubes. The bank of superheater tubes is preferably separated from the furnace combustion chamber proper by a tube wall in which the tubes are closely mounted preferably in vertical arrangement so that the tube wall separates the superheater bank from the main combustion chamber, except that the lower portion of certain of the tubes of the tube wall are bent in an offset manner so as to provide passageways for the furnace gases from the combustion chamber side of the wall to the superheater side of the wall.

A further feature of my invention is to provide a steam generator setting which includes a readily removable economizer tube bank mounted adjacent one of the side walls of the setting and in which a platform is provided on the outside of the side Wall so that the economizer tube bank may be removed from the setting for cleaning and repairing.

Another feature of my invention is to provide a steam generator unit which is of relatively simple construction and in which a combustion chamber and various heating compartments are provided and heated without the use of the usual bafiies. l

Other objects, features and advantages of my invention will be apparent to those skilled in the art from the following more detailed description thereof, taken in connection with the accompanying drawings constituting a part of this vgeneral features of construction shown in Figs.

1 to 3, in which Fig. 5 is a broken vertical sectional View and Fig. 4 is a horizontal sectional view taken on the line 4-4 of Fig. 5.

Referring to Figs. 1 to 3 of the drawings, the improved steam generator of the present invention is constructed on a foundation or setting I0. The unit -is of substantially rectangular cross-section and provided With brick and insula- M"- tion side walls l2 of usual construction which may be supported in the usual manner by a steel framework and backing plate construction, no1 shown, The unit also includes a roof I4 com prising insulation which also covers a steam and water drum l5 mounted in the upper portion of the unit. The 4generator unit of the present invention comprises a furnace or combustion chamber I1 of generally rectangular cross-section, arranged for down-draft ring, and which occupies the greater portion of the cross-sectionv` of the unit. The height of the chamber is relatively great compared to its width, and it is fired, preferably with pulverized solid fuels, from burners I8 distributed over the roof section of the unit covering the combustion chamber. The bottom of the combustion chamber Il yincludes converging downwardly sloping walls which terminate in an ash pit 22 from which ashes are removed by suitable means, not shown.

The inside'of thegenerator unit is substantially completely lined with steam generating tubes closely mounted together to form substantially continuous walls. For example, each of the side walls is provided with closely set steam generating tubes 24 which terminate in a lower header 2li and an upper header 28. Steam formed in the tubes '24 collects in the upper header and is conducted into the steam and water drum I6 by means of tubes 3i! which are distributed along the opposite headers 28. The left end wall of the unit includes an upper header `32 and a lower header 34, between which are mounted closely spaced vertical wall tubes 36. The header 32 is connected into the steam and water drum IS by spaced tubes 38 which are distributed across the roof of the unit. The burners Yi3 4are of flat constructionso that they extend between the roof tubes 38.

The opposite lend'cf the steam generating unit proper comprises a tube wall 4:3 of vertical-closely mounted steam generating tubes which terminate at their lower ends in "a header 42 Aand at their upper 'ends in the steam and -water drum i6. The upper portion ofthe tube wall vl0 is constructed -for the passage of combustion gases by bending in 'alternate tubes lof 'the wall 40, as indicated at M. It will be apparent that when every other tube of `the wall is bent in, in the manner shown, that combustion gases can pass between the tubes. Alternate tubes of the wall 4% are also bent in, as indicated at d'5, at the vbottom of the furnace, to permit ash to fall into a pit it which is provided with an inclined duct 50 'so that the ash collected therein may ilow into the pit 22. The tubes `of the wall '50 are otherwise so close together as to prevent passage of 'all but traces of combustion gases.

The vertical combustion chamber il of the generator unit is dened by the side tube walls formed by the tubes 24, the end tube wall formed by the closely mounted tubes 35, and Aby a tube wall 52 comprising Vclosely mounted steam generating tubes `adapted to substantially prevent the passage of furnace gases, the Vupper ends of which are connected into the water and steam'drum AI6 while the lower ends are confnected into the header 132 as indicated. Approximately the lower half 'of the wall 52 is Yprovided with passageways so Vthat combustion gases `can flow from the combustion chamber 'Il into `cont-act with the Wall fl-i. These passageways are formed by bending tubesll of the `wall 52 so that the lower section of the wall includes passageways "for the passage of gases, such passageways being clearly indicated in Fig. 2 of the drawings. The burners I8 distributed over the roof of the combustion chamber Il' produce an enormous quantity of retained heat, and it has been found that the efficiency of a combustion chamber of the type described can be greatly increased by providing additional steam generating tubes in front of the tube walls on all four sides of the combustion chamber. The side walls, for example, includes a row of tubes 55 which is sub- 's'tantially spaced from the tube wall and in which the tubes are substantially spaced from each other. These tubes may be from one to three tube diameters from the tube wall and are prefera'blytwo or three diameters apart. The end of the tubes 56 are bont and connected into `the :respective headers 2S and 2%, vas indicated. .A similar row of tubes 58 is also mounted opposite the 'wall tubes 36 in approximately the relationship described for the wall comprising the tubes 55. The tubes 58 are headed into Vthe headers 32 and-'34,as indicated. A similarly arranged row-oi tubes is also provided in front of the tube wall 52 and comprises spaced tubes 5E! which are headed into the water and steam drum I6 and the header 42, as indicated. The spacing ofthe tubes 6G from the Ywall 52 and from each other `is approximately the same asindicated above for `the tubes V56.

The rows of spaced tubes 56, 58 and G0 are subjected to direct radiation since they completely surround the combustion chamber, but Athey are spaced from each other to a `sufficient extent to not interfere with the eiiiciency of the closely mounted wall tubes. It has been found, lfor example, that the temperatures back of the rows of spaced tubes may still -be as vhigh as 1350 F. and that the wall tubes will receive `adequate radiation. The rows of spaced tubes therefore greatly increase the efficiency-of the unitias well as its capacity in relation '.to-itsrsize. The tubes 24 Aand 56 Vmayfbe 35 feet-long or longer, which gives an Aidea of the `size of the generator unit and the height ofthe combustion chamber.

A part of the ash from the burning of puiverized solid fuels in the burners i8 -collects Ain the pit 22 at the bottom of Ythe combustion chamber while the combustion gases pass through the lower portion of the tube-wall V52 into a narrow vertical chamber .Bil between the tube walls 40 and 52 in which is mounted a steam superheater comprising Alooped tubes 66. The superheater preferably extends entirely across the unit as indicated in Fig. 3 and comprises a plurality of the looped -tubes t5, the linlet ends of which are connected into a header 58 while the outlet ends are connected into a header 10. Steam is supplied to the header TISS "from the water and steam drum I6 through one .or more steam'lines'12. `Superheated -steam 4may be distributed from the header Hi to any desired power or heating unit. The vcombustion gases from the chamber 64 after 1heating the superheater pass through the upper portion of the wall 4Q and downwardly yin contact with van economizer tube bank comprising a 'plurality of coiled or looped tubes 'M arranged across the unit and connected `into a water inlet header "i6 and a water outlet header 13, from which water may be supplied to the steam vgenerator unit by connections and means, not shown.

The combustion gases leaving the economizer unit pass through a grating '86 lwhich supports the economizer tube vlbank above cross-beams B2 which are welded or otherwise secured into the steel structure of the steam generator unit. The hot combustion gases then pass through the tubes of an air heater` 84 and into a flue duct 86 which leads to an exhaust fan or stack, not shown. Air to bepreheated is introduced from a duct 88 and forced by a blower 00 up around the tubes of the air heater 84 from which the air is conducted through an insulated duct 92 into hot air ducts 94 for the burners I8.

Any `fine ash which may have been carried by the combustion gases from the combustion chamber over into contact with the economizer tubes 14 is dropped out in a trap 96. It will be noted that the steam superheater bank is spaced somewhat from the tube Wall 40 so that a passage is provided through which a portion of the hot combustion gases can pass along the tube wall 40 without flowing entirely in contact With the tubes 66 of the superheater. This passage is used in connection with three vertically spaced dampers 98 for regulating the temperature to which the steam is superheated. It will be apparent that if all the dampers S8 are open or vertical, a substantial part of the combustion gases will bypass a substantial part of the superheater and flow directly along the tube wall 40; whereas if the dampers are inthe position shown, all of the combustion gases will be forced to contact tubes 66 throughout their complete length. One or more of the dampers may be voperated to obtain the desired temperature for the superheated steam.

One of the common difficulties with steam generating units is the inaccessibility of the economizer tube bank from the standpoint of making repairs and tube replacements. present instance, a construction has been provided to facilitate the removal of the economizer tube bank from the setting for the purpose of making repairs and replacing tubes. Accordingly, the wall I2 adjacent` the economizer is provided with one or more removable panels |00 so that the economizer is exposed from the side of the unit. However, in order to facilitate repairs, the chamber in which the economizer is mounted is provided with a hinged door |02 In the which may be swung to the dotted line position so that the combustion gases no longer contact the economizer tube bank but pass directly down outside the wall 40 into the tubes of the air heater 84. A similar door I 04 is provided at the top of the air heater to close off the passage between the grating 80 and the air heater by swinging the door |04 to the dotted line position. With the doors |02 and V| 04 set in the dotted line positions, the panelA or panels |00 may be removed, the headers 16 and 18 disconnected from the inlet and outlet lines, and the economizer shifted outside the unit to a platform |06V which is a steel structure, including the beams 82, of suiiicient strength to accommodate the :economizer during any tube replacement or repairs.

The steam generator unit of the present invention is provided with but a single drum, that is, the steam and water drum I6 at the top of the combustion chamber. Since steam is generated in the wall tubes in all of the vertical or inclined tubes in the unit, the circulation is necessarily upward into the steam drum I6, the headers 28 and the header 32. The steam and Water ows from the headers 28 and 32 into the steam drum I6. The circulation of Water back to the lower headers 26, 34 and 42 from the steam and water drum I 6 is effected by means of down-comer pipes |08 (Fig. 2) from the opl posite ends of the Water and steam drum I6 to the ends of the headers 26, 34 and 42, as indicated. The lines |08 are shown as being connected only into one end of the headers 26 but both ends of each of these headers may be connected into the respective lines |08, if desired.

Figs. 4 and 5 are similar, respectively, to Figs.

2 and 1, except that they show a modified form ofunit or a modification of the upper portion of the unit shown in Figs. l and 2 for the purpose of admitting tertiary air to the three outer sides of the combustion chamber.

Referring more particularly to the modified showing in Fig. 5, the view corresponds to a portion of the upper left hand corner of the furnace shown in Fig. 1. In Fig. 5 a tube Wall I|0 cornprised of closely mounted tubes along the outside Wall |I2 is modified so that alternate tubes, or at least some of the tubes, of the wall I|0 are bent in slightly at ||4 so that the tubes of the wall I I0 will be spaced from each other over approximately the upper one third of the furnace so that air may be admitted to the uppe':l portion of the combustion chamber from the end and side walls of the furnace. The tubes of the Wall |I0 terminate at the top in a header |I6 which corresponds to the header 32. The upper portion of the side walls of the furnace are modified in a similar way by bending in alternate tubes of the side tube Walls I|8, the upper ends of the tubes terminating in opposite upper headers |20, corresponding to the headers 28. Air to be sup plied to the upper section of the combustion chamber may be a portion of the hot air from the duct 92 which is delivered to a horizontal duct |22. Riser ducts |24 distribute air from duct |22 through branching ducts |26, each of which is provided with a damper |28. These dampers may be operated by ,a hand lever or other connecting leverage means, as indicated. The ducts |26 deliver air into vertically spaced horizontal channels |30, |32 and |34, respectively, which open against the tube wall I0 along the section Where the alternate tubes are bent Air therefore may be delivered into any one of the channels 30, |32 or |34, or all of them, to aid in burning the pulverized solid fuel introduced through burners the same as burners I8 shown in Fig. l.

The modified form of furnace of Fig. 5 is provided with a row of steam generator tubes |36 which is spaced from the tube wall |||J and in which the tubes are spaced from each other in substantially the manner described above in connection with the rows of spaced tubes mounted opposite the tube Iwalls of the combustion chamber Tubes |36 terminate in the header I I6. A similar row of tubes |38 are provided opposite each of the tube walls ||8 and these tubes terminate in the upper headers |20. The tubes |36 and |38 are of great advantage when air is admitted through the side walls, since they absorb the increased heat.

Fig. 4 shows the arrangement of means for supplying tertiary air from the three sides of the combustion chamber which have outside Walls, the arrangement along each Wall being the same as that shown in Fig. 5. The use of tertiary air in the upper` portion of the furnace in the manner shown in Figs. 4 and 5 has been found to be very effective, particularly in the burning of pulverized anthracite coal, the primary air being supplied along with the pulverized coal, the secondary air being conducted from the ducts 94 alongside the flat burners I8, and deflected into theburning fuel immediately below the tips of `the burners, while the tertiary airis introduced into the upper portion Aof the furnace through the tube walls, as shown in Figs. 4 and 5. Thev dampers ,123 may be used torestrict the introduction of air to any of :the `three levels represented by the lhorizontal distribution passages L39, 132 and S34.

The improved steam generator unit of my inienton is adaptable for construction in various Sizes whi/le still maintaining avery high efficiency.

From the foregoing description it will be apparent that various modifications inthe details of Yconstruction and arrangement may be made' Without departing from the spirit and scope of the invention, as defined by the appended claims.

What is claimed as new is:

1. In an economizer construction, walls including an outside Wall dening an economizer chamber through which heating gases are .adapted to pass, an economizer tube bank mounted in said chamber and arranged to be heated by the heating gases passing therethrough, a bypass chamber for heating gases parallel to the eccnomizer chamber and separated therefrom by one of said walls, a swinging door associated with the wall separatingvsaid chambers at both the inlet and outlet -ends of the economizer chamber and adapted to close 01T either 0f said chambers to the passage of heating gases, and a platform on the outside of and alongside said outside wall adjacent to the position of the economizer tube bank and extending laterally from said Wall at a position directly below the economizer tube bank, a section of said outside wall above said platform and along 'the position of the economizer tube bank being readily removable so that access may be had to the economizer tube bank, the arrangement ,being such that said doors may close 01T the economizer chamber Vso that the economizer tube bank may be lremoved from the economizer chamber onto the platform for cleaning and repairs 'while continuing the passage of `said heating gases through said bypass chamber.

2. An eccnomizer construction as dened by claim l characterized in that .the platform includes supporting structural members extending through said outside wall and under the .economizer tube bank as a supporting means therefor in the economiser chamber.

JOSEPH E. KENNEDY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,132,225 Stevens Mar. 16, 1915 1,296,233 'Trevithick Maix, 1919 1,764,172 Keenan, Jr. June '17, 1930 1,851,842" Huster Mar. 29, 1932 2,003,419 Artsay June 4, 1935 2,139,348 Badenhausen Dec. 6, 1938 2,325,583 Artsay Aug. 3, 1943 2,418,815 Bayer Apr. 15, 1947 FOREIGN PATENTS Number Country Date 454,408 Germany Jan. '7, 1928 773,477 France Sept. 3, 1934 

